Field
Embodiments described generally relate to paperboard blanks for paper products, methods for making same, and paperboard products therefrom. More particularly, embodiments described generally relate to cup stock.
Description of the Related Art
Fibrous substrates, such as paper and paperboard, are used in food service applications to make a wide variety of paper products, such as plates, bowls, and cups. Some specific uses require a heat-seal step in the converting operation such as paper products used in canister applications. Products resulting from paper and paperboard can have poor resistance to water, gases, oils, solvents and greases unless treated to improve the barrier properties of the paper. For example, to improve the water resistance properties of paperboard used to make disposable cups, the paperboard is typically coated with a hot-melt extruded polyethylene on one or both sides of the paperboard stock. For hot applications, the polyethylene layer is disposed on the inside of the cup and bonded to bare or clay-coated paperboard on the opposite side. For cold applications, the outside of the cup needs to be water resistant to prevent damage of the paperboard by condensation, so the outside is also coated with polyethylene, and the two polyethylene surfaces are heat sealed together at the side seam. The bottom stock is similarly matched such that a polyethylene coated paperboard surface is heat sealed to the inside surface of the cupstock, which is also polyethylene coated.
Although polyethylene coatings serve as good water barriers and are fairly inexpensive, there is a continuous effort to develop alternatives to melt extruded polyethylene, particularly for paper cups. For example, a liquid-based polymeric dispersion or emulsion is an alternative to melt extruded polyethylene. A particular motivation of applying the barrier in the form of a liquid-based polymeric dispersion or emulsion, and then drying to form a continuous film, is related to sustainability. Less material may be used, as stability requirements pertaining to the extruded melt curtain are obviated. Dispersion-coated barriers are also generally more repulpable and hence more recyclable than extrusion-coated barriers.